Modified annular ring slot antenna for dual WLAN band application

In this paper, the modified annular ring slot antenna is proposed for 2.4/5-GHz dual WLAN band operation. The higher order resonant modes in the annular ring slot are used to control the second operating frequency. The proposed antenna is printed on a FR-4 substrate, and has dimensions of 50 times 50 times 1.2 [mm] with a ground plane. The frequency ratio of the two operating frequencies can be adjusted from 1.97 to 2.64 with geometric values. The measured impedance bandwidths (VSWR<2) of the proposed antenna are approximately 13.2% for the 2.4-GHz band and 40% for the 5-GHz band and the peak gains are 3.74, 4.12 and 5.25 dBi for 2.45, 5.35 and 5.8 GHz bands, respectively.